Abstract:

For daily chemical cleaning products, the size, compactness and stability of the foam can be easily perceived by consumers, which may even directly affect the comprehensive evaluation of the products. Therefore, the evaluation of foam performance is very important. Herein, the testing method and principle of dynamic foam analysis were introduced. The transmission light could be measured with time using LED panel and side line sensor. The liquid/foam and foam/air boundaries could be detected by light intensity difference, and the foam decay process in the measurement cycle could be read out through the line sensor. This testing method was used to test the foams of common raw materials of surfactants and conventional daily cleaning products such as laundry detergents, shampoos, and toothpastes. Differentiated test procedures were set for different samples. Then the evolution of foam height （h_foam）, foam volume （V_foam）, number of bubbles per square millimeter （BC）, average area of bubbles （MBA）, average radius of bubbles （R_avg） and other parameters over time was monitored in the whole test period. Through the analysis of foam volume, foam height and other parameters in the height test module, the foaming abilities of the products were evaluated; by analyzing the number of bubbles, the average bubble area and the average bubble radius in the structure test module, the foam micro-structure was evaluated; the foam stability was evaluated by analyzing the parameters of foam volume fraction, maximum foam liquid carrying capacity, half-life of bubbles, etc. Therefore, based on the characteristics of daily chemical products, setting up different automatic test programs and analyzing the foam performance with the combination of the parameters in each test module can effectively realize the multi-dimensional evaluation of foam performance, so as to guide the development and optimization of new products.

Key words: foam height, foam structure, foam stability, defoaming rate, half-life